This invention relates generally to advertising, and in particular to real-time bidding for advertising impressions in social networking and other online systems.
Advertisers pay various online systems to present their advertisements (“ads”) to users of the online systems. The advertisers often seek to present ads to users likely to be interested in their products or services and most likely to purchase the advertised products or services. Accordingly, if a user of an online system is more likely to purchase an advertised product or service, an advertiser may increase the amount paid to the online system to present the ads to that user.
To identify users likely to interact with an advertisement or likely to purchase advertised products or services, advertisers or advertising partners often store online browsing activity of users. Based on users' browsing activity, the advertiser or advertising partner may increase the amount offered to an online system to present advertisements to users that visited certain websites or purchased certain items. However, advertisers typically index stored browsing activity based on the browser used to perform the browsing. Because users may use multiple browsers for online browsing, and multiple users may use the same browser, advertisers may incorrectly target their advertisements if they rely on browser-indexed history to identify potentially-interested users.